The invention relates to the start/stop control of conveying means in material handling systems.
While the invention is applicable to material handling systems of various kinds, including, for example, luggage checkin systems in airports or bus terminals, the preferred application of the invention is in connection with automated checkout systems in retail stores, particularly grocery stores or super markets, and it will hereinafter be described as applied to such systems. The conveying means are preferably in the form of conveyor belts but the invention is of equal merit when applied to turntables or similar conveying apparatus.
In systems of the above type it is known to provide at the delivery end of the incoming conveyor belt, that is, at the end of the belt adjacent the checkout stand proper, a sensing device which responds to the breaking of a light beam by the product first in line arriving at that end to automatically stop the normally operating belt. As the checkout clerk lifts the product from the belt to check it out, the light beam again strikes the scanning device and, as a result, the conveyor belt is restarted. This cycle repeats itself as the product next in line reaches this end of the conveyor belt and so on.
At slack times, when the product "traffic" on the conveyor belt leading to the checkout system is light or becomes non-existent, that is when, at least temporarily, no further products are being placed on the belt by waiting customers, the belt would keep running since the sensing device would cease to detect arriving products. As a consequence there would be unnecessary wear and tear on the belt and its driving equipment and this would be accompanied by a corresponding waste of energy.